1. Field of the Invention
This invention relates to a 3-axis straight-line motion stage for making a 3-axis straight-line motion, and particularly relates to a 3-axis straight-line motion stage and a sample test device using the same for supporting a predetermined sample, and comprising X-axis, Y-axis and Z-axis stages for moving the sample independently and precisely in the direction of the X-axis, the Y-axis or the Z-axis of rectangular coordinates.
2. Description of the Background Art
Generally, a stage used for scanning a predetermined sample in the direction of the X-axis, the Y-axis or the Z-axis on the basis of rectangular coordinates within an atom microscope uses a piezoelectric element, such as a piezotube, and moves the sample precisely.
FIG. 1 is a constitutional view for explaining an operational principle of stage embodied using a piezotube.
The piezotube is a piezoelectric element that generates the negative and positive electric charge in proportion to the magnitude of the pressure received from the outside, whereas its length is increased or decreased in proportion to the magnitude of the voltage in case of receiving the voltage. As shown in FIG. 1, if the voltage from the electric power source is applied to the both ends of the piezotube 100, the length of the piezotube 100 is increased by L from L0, which means the length before the voltage is applied, to change to L0+L, simultaneously the diameter in the same radial direction perpendicular to the longitudinal direction thereof is decreased by −D from D0, which means the diameter before the voltage is applied, to change to D0−D. Thus, a sample supported by the piezotube in a stage where the above cylindrical pizeotube 100 is mounted may be shifted finely in the longitudinal and radial direction thereof according to the motion of the piezotube 100.
However, since the motion to the radial direction of the X-axis and the Y-axis and the motion to the longitudinal direction of the Z-axis of the piezotube supporting the sample are mutually dependent in the stage where the piezotube is mounted, when a user manipulates the piezotube to shift the sample in the desired direction of the X-axis or the Y-axis, the sample is simultaneously shifted to the undesired direction of the Z-axis. Thus, the displacement generated due to the shift in the undesired direction of the Z-axis should be compensated.
However, since a correlation between the displacement generated form the piezotube and the direction of the displacement thereof is unclear, even if the procedure for compensating the displacement of any direction is prosecuted, another error may be included in the compensating value during the compensating procedure. Thus, there has been a problem that the prior stage using the shape and characteristic of the piezoelectric element cannot shift the sample precisely.
In order to resolve the problem of the prior stage, a straight-line motion stage for shifting the sample using the displacement of one direction (the displacement of the straight-line motion) of the piezoelectric element has been developed.
FIG. 2 is a constitutional view of the prior straight-line motion stage having a lever type flexible mechanism. The mechanism shown in FIG. 2 is consisted of a lever 90 having a predetermined length, a flexible hinge 91 being a rotation center of the lever 90 and one end thereof being fixed, and a support 94 mounted on the other end opponent to the attaching side for the flexible hinge 91 for supporting the predetermined sample.
According to the mechanism, for example, if a force 93 of a predetermined magnitude is applied to a point P1 adjacent to the rotation center O of the lever 90 so that the lever 90 is rotated at the rotation displacement T1, a point P2 of the lever, on which the support 94 is mounted, is rotated at the rotation displacement T2. Here, the rotation displacement T2 of the point P2 to the rotation displacement T1 of the point P1 is proportional to the ratio of the distance from the rotation center O to the point P1 to the distance from the rotation center O to the point P2 {T2=(T1)(P2)/(P1)}.
However, even if the piezoelectric element having a range of several to several tens  amplifies the displacement range thereof through the lever 90, since the displacement from the end of the lever 90 is generated in the circumferential direction, the sample placed in the end of the lever is not shifted completely in the straight-line direction.
Meanwhile, in order to resolve the problem of the stage having the above mechanism, a double spring stage having a double straight-line spring mounted on the lever has been developed. However, the double straight-line spring stage also does not shift the sample placed in the lever in the straight-line direction.